zebra: clean up client routes when client goes away

  * zebra/zebra_rib.c: Add code to clean up routes added by a client
    (as identfied by 'rib type').

  * zebra/zserv.[ch]: Maintain the type of the routes added by a
    client on the 'zserv' structure -- assume that a given client uses
    a single route type for now.

    Clean up routes from a client when the client goes away (in
    zebra_client_close()).

From: Josh Bailey <joshb@google.com>
Signed-off-by: Avneesh Sachdev <avneesh@opensourcerouting.org>
Signed-off-by: David Lamparter <equinox@diac24.net>
diff --git a/zebra/zserv.c b/zebra/zserv.c
index 9e6f625..2330135 100644
--- a/zebra/zserv.c
+++ b/zebra/zserv.c
@@ -750,6 +750,13 @@
   
   /* Type, flags, message. */
   rib->type = stream_getc (s);
+  /* Update client's route type if it is not done yet. */
+  /* It is done here since only zread_ipv4/6_add() and
+   * zread_ipv4/6_delete() decode Zebra messages and retrieve
+   * route types. */
+  if (client->route_type == ZEBRA_ROUTE_MAX)
+    client->route_type = rib->type;
+
   rib->flags = stream_getc (s);
   message = stream_getc (s); 
   rib->uptime = time (NULL);
@@ -924,6 +931,11 @@
 
   /* Type, flags, message. */
   api.type = stream_getc (s);
+  /* Update the route type of the client. 
+   * Same as in zread_ipv4_add(). */
+  if (client->route_type == ZEBRA_ROUTE_MAX)
+    client->route_type = api.type;
+
   api.flags = stream_getc (s);
   api.message = stream_getc (s);
 
@@ -1077,6 +1089,14 @@
 static void
 zebra_client_close (struct zserv *client)
 {
+  struct stream *s;
+
+  /* Sweep all routes learned from the client first. */
+  rib_sweep_client_route(client);
+  /* Reset the route type. It may not be necessary since the
+   * whole client will be freed. */
+  client->route_type = ZEBRA_ROUTE_MAX;
+
   /* Close file descriptor. */
   if (client->sock)
     {
@@ -1115,6 +1135,9 @@
 
   /* Make client input/output buffer. */
   client->sock = sock;
+  /* Set the default route type to ZEBRA_ROUTE_MAX; it will be updated
+   * once new routes are received. */
+  client->route_type = ZEBRA_ROUTE_MAX;
   client->ibuf = stream_new (ZEBRA_MAX_PACKET_SIZ);
   client->obuf = stream_new (ZEBRA_MAX_PACKET_SIZ);
   client->wb = buffer_new(0);